Frequency controlled electronic oscillator



April 5, 1938. l. woLFF 'FREQUENCY CONTROLLEDELECTRONIC OSCILLATOR FiledJul-y 25, 1936 nventor gyf (Ittc'xneg Nek Y N Patented Apr. 5, 1938FREQUENCY ooNTnoLLED ELEc'rtaoNio osoILLAToR Irving Wolff,Merchantville, N. J., assigner `to Radio Corporation of America, acorporation of Delaware Application July 25, 1936, Serial N0. 92,614

6 Claims.

In its broad aspects, this invention relates to electronic oscillators.More specifically, the invention is a carrier frequency control for amodulated electronic oscillator. y

An electronic oscillator or magnetron may be used to generate ultra highfrequency oscillatory currents; i. e., currents of a frequency of thirtymegacycles and upwards. If a magnetron oscillating at three thousandmagacycles, by Way of example, is modulated, the modulation currentsWill not only modulate the amplitude of the oscillations but willgreatly vary the frequency of the carrier current. This inventioncontemplates stabilizing the frequency of the carrier current of amodulated magnetron oscillator.

One of the objects o-f my invention is to provide means for stabilizingthe frequency of an electronic oscillator. Another object is to -providean oscillator for controlling the frequency of the carrier currents of amodulated magnetron oscillator.

A further object is to provide means for preventing a controllingoscillator from being affected by the oscillator to be controlled.

In the accompanying drawing, Fig. 1 represents a schematic illustrationof my invention, and

Fig. 2 is a circuit diagram of a modulated vmagnetron oscillator Whosecarrier frequency is controlled.

Referring to Fig. 1, a magnetron oscillator I is adjusted to establish acarrier frequency of 3000 megacycles, by Way of example. Signalling ormodulating currents are impressed on the oscillator I by a modulator 3.The effect of the modulation currents is to vary both the amplitude andfrequency ofthe carrier current. rI lie frequency may be stabilized orcontrolled Aby impressing` currents of carrier frequency, which areunmodulated, on the modulated oscillator. If the control currents ofcarrier frequency are impressed directly from the control oscillator 5on the unmodulated oscillator I, the resulting frequency Will bedetermined by the relative reaction of the two oscillators. 'I'hat is,the control oscillator 5 may control the oscillator I or be controlledby that oscillator.

The interaction may be prevented by generating currents of a frequencyof 1500 megacycles. The currents of 1500 megacycles frequency aretransferred to the oscillator I through a frequency doubler 'I. Thefrequency doubler, as the title implies, increases the control frequencycurrents from 1500 megacycles to 3000 tional Amodulated"'magnetronvoscillator 9.

megacycles. The frequency doubler not only increases the frequency butit also prevents controlled and controlling oscillators frominteracting. Thus the oscillator I is 'frequency controlled orstabilized by the control oscillator 5. Modulation currents may now beimpressed on the oscillator I and Will vary the amplitude of oscillationWithout varying the frequency of the carrier currents.'

One embodiment of my invention is `.illustrated l in Fig. 2.'Ihe'magnetronfoscillatorl is composed of Van evacuated envelope.' I I.A pair of anodes I34 and a cathode 'I5 are suitably.v mounted vWithinthe envelope III. A magnetic eld, Whoselines of forceare substantiallyvparallel to and surround the fcatho'de, is establishedby a solenoid II',permanent rnagnet, or the like. The

solenoid I1 may beenergized by a battery I9.

The cathode I5 is heated' by a battery2l. The anodes I3Vare' connectedto a resonant transmission line 23 which terminates in a dipole antenna25. The anode circuit is comprised of an anode battery 21, which isserially connected, through the secondary 29 of a Ymodulationtransformer 3l and-radio frequency choke coil 33,@2

to la point intermediate lthe ends of the ydipole 25. The modulation iseffected by a microphone which is connected through a battery 31 to thevprimary 39 of the modulation transformer 3|.

The circuit thus farydescribed is a conven- The control oscillator 4I,'Which'operate`s at half the carrier frequency of themodulated oscillator9, is comprised of an evacuated envelope 43 which includes a cathode 45and a pair of anodes 41..

'The envelope is surrounded by a solenoid 49 Which is energized by abattery, 5I. The cathode 45 is energized'bya ybattery 53. The anodes 4Iare connected to a resonant transmission line 'T40 55.` An anode battery5I is connected from the cathode 45 through a radio frequency choke coll59 to the mid-point of the transmission line 55.

The transmission line 55 is suitably coupled to another transmissionline 6I. The latter transmission line is terminated in a full waverectifier 63, Whose output currents are of double the frequency of theinput currents. vThe output of the rectier is impressed on a pair ofenclosed quarter Wave lines 65, 61 between terminals which offer asuitable impedance match for the full Wave rectifier, or frequencydoubler.

The quarter Wave lines 65, 61 are respectively connected to thetransmission line 23 by leads 69, 1I which include "trombones 13, 15 orthe like, for tuning the connecting lines S9-l I. The severaltransmission lines may be terminated in sections of line which offersuitable impedances. Inasmuch as constant frequency is desired, theoscillators and transmission lines should be carefully designed andconstructed to minimize changes caused by the ambient temperature,vibration, voltage variations, and the like.

Thus I have described a modulated magnetron oscillator. The carrierfrequency currents generated by this oscillator are controlled. Thecontrolling oscillator creates unmodulated oscillatory currents whichhave half the frequency of the modulated carrier currents. The frequencyof the controlling oscillator currents is doubled by full Wave rectiiersor the like. The controlling currents of the frequency of the carrierare impressed through suitable transmission lines on the modulatedmagnetron oscillator to stabilize or control the frequency of thecarrier currents and thereby prevent frequency modulation.

Although I have chosen magnetron oscillators to illustrate my invention,it should be understood that Barkhausen-Kurz or any type of ultra highfrequency oscillatormay be used. Like- Wise the controlling frequencymay be made less than half of the carrier and multiplied by more thantwo to control the carrier frequency.

I claim:

1. An ultra high frequency system comprising an ultra high frequencyoscillator for generating carrier frequency currents, means forimpressing modulating currents on said oscillator, a second oscillatorfor generating currents of less than said carrier frequency, means formultiplying the frequency of said controlling current to equal thecarrier frequency, a pair of resonant lines for stabilizing thefrequency of said multiplied frequency currents, means for impressingsaid multiplied frequency currents on said pair of resonant lines, andmeans for impressing said multiplied and stabilized frequency currentson said ultra high frequency oscillator to thereby control said carrierfrequency currents.

2. An ultra high frequency system comprising an ultra high frequencyoscillator for generating carrier frequency currents, means forimpressing modulating currents on said oscillator. a second oscillatorfor generating currents of -half said carrier frequency, means fordoubling the frequency of said controlling currents, a pair of quarterwave resonant lines for stabilizing the frequency of said doubledfrequency currents, means for impressing said doubled frequency currentson said pair of resonant lines, and means for impressing said doubledand stabilized frequency currents on said ultra high frequencyoscillator to thereby control said carrier frequency currents.

3. An ultra high frequency system comprising a magnetron oscillator forgenerating carrier frequency currents, means for impressing modulatingcurrents on said oscillator, a second oscillator for generating currentsof less than said carrier frequency, means for multiplying the frequencyof said controlling currents to equal the carrier frequency, a pair ofquarter wave resonant concentric lines for stabilizing said multipliedfrequency currents, means for impressing said multiplied frequencycurrents on said pair of concentric lines, and means for impressing saidstabilized multiplied frequency currents on said magnetron oscillator tothereby control said carrier frequency currents.

4. An ultra high frequency signalling system comprising, in combination,a magnetron oscillator for generating carrier frequency currents, meansfor modulating said carrier frequency currents with signal impulses, asecond oscillator for generating controlling currents of half saidcarrier frequency, means for impressing currents from said secondoscillator on a full Wave rectifier, a pair oi' enclosed quarter wavelength lines resonant to the output currents from said rectifier forstabilizing the frequency of said rectifier currents, means forimpressing said rectified currents on said quarter Wave length lines,and means for impressing the output currents thus stabilized on atransmission line coupled to said magnetron oscillator for controllingthe frequency of said carrier currents.

5. The method of controlling the frequency of modulated ultra highfrequency carrier currents by means of a concentric resonant line whichcomprises generating an ultra high frequency carrier current, modulatingsaid carrier current, and generating an unmodulated controlling currentof a frequency equal to said carrier, stabilizing the frequency of saidunmodulated controlling current by applying said current to saidconcentric resonant line, and applying said frequency stabilizedcontrolling current to said modulated ultra high frequency carrier tocontrol the frequency of said carrier currents.

6. The method of controlling the frequency of modulated ultra highfrequency carrier currents by means of a resonant line which comprisesgenerating an ultra high frequency carrier current, modulating saidcarrier current, generating an unmodulated controlling current of lowerfrequency than said carrier frequency, multiplying said lower frequencycurrent until its frequency equals said carrier frequency, stabilizingthe frequency of the currents of said multiplied frequency by applyingsaid multiplied frequency currents to said resonant line and impressingsaid multiplied and stabilized frequency current on said modulated ultrahigh frequency carrier to control the frequency of said carriercurrents.

IRVING WOLFF.

